This invention relates to a cutter for a mower, and more particularly to a cutter for a mower which cuts grass by rotating flexible synthetic resin wire-like cutting members at high speed.
The prior art mowers generally cut grass by rotating metal cutting blades at high speed, and there is a possibility of injury to persons from the rotating blades when the mowers are mishandled while cutting grass in gardens, parks, highway separation areas and the like.
Furthermore, when trimming grass around trees, flower-beds, road shoulders and the like, there is the possibility that the cutting blade will strike such obstacles, which occasionally leads to loss of control of the mower, damaging the blades and throwing pieces thereof, and damaging the trees etc.
To overcome these disadvantages, a mower that cuts grass at high speed by means of rotating flexible synthetic resin cutting members or wires instead of metal cutting blades has been developed.
The mowers of this kind are two types: one has a rotating disc which has an adequate number of apertures in the periphery thereof and is attached to a tip of a rotating shaft, and flexible wire-shaped cutting members are fixed in the apertures of the rotating disc -- that is, no replacement wire-shaped material is provided in the rotating disc; and the other contains a flexible wire-shaped cutting members wound in a spiral in the rotating disc attached to a tip of the rotating shaft with ends projecting from the disc -- that is, replacement wire-shaped material is provided in the rotating disc.
Compared with a lawn mower using metal cutting blades, a lawn mower of this kind is safer and is capable of trimming grass around trees, flower-beds, road shoulders and the like with ease and without damaging such objects.
This type of mower is described in United States Pat. Nos. 3,708,967 and 3,859,776, etc.
The former type cutter having no built-in replacement wire-shaped cutting material has advantages from the standpoint of reliability and cost because of its simple construction.
In the U.S. Pat. No. 3,708,967, there is disclosed a rotating disc which has a plurality of apertures adjacent the periphery thereof, holes extend radially from the apertures to the periphery, cutting lines pass through the apertures to the outside of the disc, and knotted ends of lines in the apertures prevent the lines from being flung off the disc during its rotation.
However, since the line material is of sufficiently hard synthetic resin to withstand impact with grass and the like and has a large diameter, it is extremely difficult to knot the ends and it requires much skill and a relatively long time to pass the lines through the holes.